Greenbrier is located in Robertson county Tennessee with a geographic area of 7.3 square miles. The total population in Greenbrier is 6,859 with 46.1% male and 53.9% female. Children under age 5 represent 6.0% of the population, under age 18 equal 30.2% of the population and over age 65 is 8.8% of the population. The median household income is $69,381, per capita income is $27,901. There are a total of 2,192 housing units with 77.8% owner occupied. Education includes 35.6% of residents that are high school graduates and 23.7% with a bachelor's degree or higher. The average temperature in Greenbrier in the summer is 77 degrees, and in the winter 38 degrees.